1. Field of the Invention
The present invention relates to an apparatus and method for continuity testing of pogo pins, particularly to an apparatus and method for continuity testing of pogo pins in a probe for semiconductor device testing.
2. Description of the Prior Art
FIG. 1 is a diagram showing a probe for semiconductor device testing. A probe 1 comprises circularly arranged pogo pins 11 and 12 which provide ground and test signals to a wafer being tested (not shown) respectively. Since the elasticity of the pogo pins 11 and 12 may be worn, which results in a contact fault, a continuity test of the pogo pins 11 and 12 is needed before the wafer can be tested using the probe.
Conventionally, the continuity test is implemented with the wafer under test put in the probe 1, a probe card and a test head mounted on the pogo pins 11 and 12. The results of the continuity test appear on a screen of the test head.
However, there are several drawbacks to the conventional continuity test method.
1. Contact faults of the pogo pins 11 for ground signals cannot be detected since all of them are electrically connected in the probe 1.
2. Alignment of the wafer under each test is necessary. Thus makes the continuity test time-consuming.
3. The operator must check hundreds of results appearing on the screen of the test head and a refresh of the results takes 1xcx9c2 seconds due to the long response time of analog-to digital converters.
There is an alternative method for continuity testing, wherein a sheet of carbon paper is applied to the pogo pins and the operator can detect failed pogo pins by inspecting the imprints on the carbon paper. This method, however, introduces carbon contamination to the pogo pins and the probe.
Therefore, the object of the present invention is to provide an apparatus and method for continuity testing of pogo pins in a probe, in which the wafer, probe card and test head are not necessary and the operator can easily identify the failed pogo pins.
The present invention provides an apparatus for continuity testing of a pogo pin in a probe. The apparatus comprises a substrate having a pad, a power supply providing a voltage difference between pad and pogo pin, and a sensing device signaling when the substrate contacts the probe and a current is generated by connection of the pogo pin and the pad.
The present invention further provides a method for continuity testing of a pogo pin in a probe. The method comprises the steps of providing a substrate having a pad, generating a voltage difference between the pad and the pogo pin, placing the substrate into the probe, and signaling when a current is generated by connection of the pogo pin and the pad.
In the present invention, LEDs are used to detect contact faults between the pogo pins and the pads. The failed pogo pins do not form closed loops in which currents are generated by the voltage difference. The LEDs corresponding to the failed pogo pins remain unlit.